You raise very timely and pertinent questions about MP Materials Corp. (ticker: MP) and the broader U.S. rare-earths / U.S.-China supply-chain dynamic. Below is a structured view on both your questions — again, this is not investment advice, but an analytical assessment.

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1. Is it an “add-on opportunity”?

Short answer: yes, but with caveats. It could make sense as a selective addition, if you believe the strategic thesis plays out — but you must also accept significant execution and commodity-cycle risk.

Supporting arguments

MP Materials is very well positioned in a strategic niche: It is one of the very few U.S.-based rare-earth players able to claim a vertically integrated supply chain (mine → processing → magnets) in a sector dominated by China. 

The geopolitical / strategic narrative is strong: The U.S. (and its allies) increasingly view rare-earths as critical inputs for EVs, defence, wind, electronics, etc. China continues to dominate refining and magnet manufacturing. 

MP has secured notable partnerships / support: For example, a deal with the U.S. Department of Defense (DoD) to help build a U.S. supply chain. 

This kind of strategic “tailwind” (geopolitics, supply-chain re-shoring) can create favourable pricing and margin structures if the company executes well.

Key risks / caveats

Execution risk: The path from mining rare-earth oxides → separating heavy/critical rare‐earths → manufacturing magnets at scale is very complex. MP faces ramp-up challenges. 

Commodity/price risk: Rare-earth element (REE) prices are volatile, subject to global supply/demand swings, and exposure to China’s dominant refining/processing. A large part of upside depends on favourable pricing and demand. 

Valuation & momentum risk: The stock has already run up substantially and may carry significant “hope premium”. That means upside may be more limited unless many good things happen. 

Time horizon: Many of the benefits may materialise only over the medium to long term (several years) rather than immediately.

Regulatory / geopolitical risk: While geopolitics is a tailwind, it’s also unpredictable (policy changes, supply-chain shocks, etc).

My view

Given the above, if I were investing:

I would consider adding MP Materials as a strategic long-term hold, not as a near-term trading hit.

I would allocate only a reasonable portion of my portfolio to it (given the risks) rather than overload.

I would treat any entry somewhat opportunistically: i.e., if there is a pull-back or weakness I might add — less so chasing at the top.

I would also keep the time horizon at 5 years+ and be ready for volatility.

I would monitor key catalysts (magnet facility ramp, heavy rare-earth extraction, margin improvements, government contracts) closely.

Thus: yes — I view it as an “add-on opportunity” but not without significant risk. If you believe the narrative (U.S. supply-chain de-risking + REE demand growth) then this could be an attractive way in.

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2. Would I consider MP Materials a long-term play amid U.S.–China tensions?

Yes — I believe it could serve as a meaningful long-term play, provided you believe two central assumptions hold true: (A) the U.S. (and allies) significantly ramp up domestic rare-earth/magnet supply chains, and (B) demand for rare-earth magnets / materials (EVs, defence, wind, robotics) grows robustly.

Why it fits the “long-term play” framing

Supply-chain resilience is becoming more important: With China’s dominance in REE refining/processing, any shift by the U.S. to reduce dependency is a structural change rather than a short-term blip. 

MP Materials is among the very few (if not the only) U.S. player with a scaled mine and ambitions for full value-chain integration. 

The business intersects with secular growth themes: EVs, wind turbines, defence, electronics — all of which rely on high-performance magnets (not just basic rare-earth oxides).

Government support / policy tailwinds may persist: With national-security implications and infrastructure/decarbonisation agendas, there is reason to believe favourable policy could persist.

What to watch / where the long-term “bets” lie

The ramp of magnet production: The facility ramp-up (e.g., the “Independence” facility, “10X” plant) and margin realisation will be key.

The mix of rare-earths: MP’s strength is in certain light rare earths (Nd/Pr) but heavy rare earths (e.g., dysprosium, terbium) are more difficult and China dominates them. How MP manages this gap will matter. 

Pricing/contract structure: For long-term durability they will need stable contracts, good margins, and ideally moving up the value chain (magnets vs raw materials).

Competitive dynamics: China will not stand still; other countries/miners will also scale. The “market” may become more crowded, and pricing may come under pressure.

Execution risk and capital intensity: These are infrastructure-heavy, process-heavy operations. Delays or cost overruns could hurt returns.

My verdict

Yes — I would consider MP Materials as a long-term strategic holding in a portfolio with appropriate risk tolerance. If I were building out a “strategic materials/infrastructure/defence” sleeve of a portfolio and believed in U.S. realignment of supply chains, MP makes sense. The caveat: it’s not a “safe” or “low-volatility” holding. It is a bet on structural change and thus carries significant risk and reward.

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Final Thoughts

If you believe the U.S.–China tensions over critical materials will escalate or persist, and policy will favour domestic production of rare-earth magnets etc., then MP Materials is one of the few public companies you might use to express that conviction.

But you should treat it like a strategic, high-risk, high‐reward infrastructure/industrial play, not like a broad market average.

It would likely make sense to view it as one part of a diversified exposure — e.g., alongside other players in critical minerals, processing, and supply-chain enablers — rather than putting “all your chips” on one company.

Keep a long time horizon and monitor the actual execution (facility ramps, contract wins, margin expansion) rather than just the headline narrative.