US Secretary of State Antony Blinken has told Ukrainian President Volodymyr Zelenskyy that the latest American military aid package, which has begun arriving in the country, will make a "real difference" against the ongoing Russian aggression.

Blinken's visit to Kyiv on Tuesday follows the resumption of US military support for Ukraine last month after Congress approved a long-delayed foreign assistance package.

Washington also announced last week a 400-million-dollar military aid package that includes additional munitions for Patriot air defense systems, artillery rounds and armored vehicles.

Zelenskyy offered thanks for what he called "crucial" US aid, but also stressed that more air defense systems are needed.

The Wall Street Journal reported on Monday that Ukraine is shooting down a far smaller proportion of Russian missiles than earlier in the war.

The Journal said based on its analysis of daily data from the Ukrainian Air Force Command that in the past six months Ukraine intercepted around 46 percent of Russian missiles, compared to 73 percent in the preceding six months.

The paper said the interception rate fell to 30 percent in April. It attributed the worsening performance partly to Russia's strategy of using more elusive weapons, such as ballistic missiles. It also said Kyiv is running low on ammunition for its Western-supplied Patriot air defense systems.