Democrats in the new Congress must investigate the president’s handling of Russia’s support for Iran. Reports from November 5 show Moscow provides intelligence and drone technology to help attacks against US forces. Lawmakers need to ask why the president chose not to respond, as this is their most urgent duty.

Your report (November 5) that the Democrats' new congressional majorities will find legislation constrained by presidential vetoes makes their investigative powers especially important.

Their first duty must be to examine the US president's handling of Russia's support for Iran. American officials have said that Moscow has supplied Iran with intelligence, satellite imagery and drone technology to assist attacks against US forces, placing those forces at greater risk.

Vladimir Putin has publicly pledged Russia's continued support for Tehran. Instead of demanding that Russia stop, President Trump has spoken warmly of Putin, cast doubt on the intelligence and relaxed pressure on Russian oil.

Congress must establish what the president knew and why he chose not to respond. A commander-in-chief who will not confront a foreign power helping a hostile state endanger American troops may be failing in his most fundamental duty.

This must be Congress's most urgent inquiry.