Russia and China could become more assertive over the next two years if they conclude that President Donald Trump is politically weakened after Democrats won control of both chambers of Congress, Brookings Institution senior fellow Robert Kagan told CNBC.

Speaking on “Squawk Box Asia,” Kagan said the war with Iran had highlighted limits in U.S. military capacity that could matter in Asia. He pointed to depleted stocks of missile interceptors and other munitions, which he described as important to the region.

Congressional Budget Office reports have estimated that the conflict has used as much as two-thirds of U.S. missile-defense interceptors since June 2025, largely in efforts to protect Israel from Iranian attacks. The resulting shortages could constrain U.S. inventories for several years, the reports said.

Kagan also said that sending three U.S. aircraft carriers to the Middle East had reduced the naval presence available in Asia, potentially giving China more room to act assertively. He argued that Trump’s focus on economic deals with China, rather than confronting Beijing, could encourage further Chinese aggression.

The United States approved an $11 billion arms package for Taiwan in December, but Trump later held back a second package worth about $14 billion, describing it as a “bargaining chip” in negotiations with China. Beijing claims self-governing Taiwan as its territory. Although Washington has no mutual defense treaty with the island, U.S. law requires it to provide Taiwan with the means to defend itself.

Kagan’s remarks come as the United States, China and Russia discuss a possible trilateral meeting between Trump, Chinese President Xi Jinping and Russian President Vladimir Putin at the APEC Leaders’ meeting in Shenzhen later this month. China’s Foreign Ministry said Wednesday that Beijing was in communication with relevant parties about a meeting, but no agenda had been announced.

Kagan said both Moscow and Beijing might view the next two years as a time to act if they believe Trump is on his way out and the United States could return to a more normal political footing.

Sources: CNBC Markets.