The Trump administration has done "little to hold North Korea to account" after repeated missile tests, and should "step up" enforcement of sanctions on the country, a bipartisan pair of U.S. Senators wrote this week in a letter to the State and Treasury Secretaries.

The letter -- written by Senator Bob Menendez, the top Democrat on the foreign relations committee, and Senator Cory Gardner, the Republican chair of the committee's East Asia panel -- comes after North Korea conducted four rounds of missile tests last month, all while the coronavirus was spreading rapidly around the world.