Russia's leader Vladimir Putin was reportedly often frustrated with former U.S. President Donald Trump for having to explain things on geopolitical issues, according to a former top Russian advisor on the National Security Council Fiona Hill.

Hill served in the position during the Trump administration. She added that the issue played into Moscow's decision on the timing of Russia's invasion of Ukraine, according to a Business Insider report.

Hill added that one of the reasons Putin invaded Ukraine amid U.S. President Joe Biden's presidency was that he "expected the United States to sue for peace."

The former Russian adviser said that Putin thought it would be better to deal with Biden than try to "negotiate with someone like Trump."

Hill said that the Russian leader had to "explain everything all the time" when it comes to Trump, adding that Putin does not like to do that.

Trump's former advisors have earlier said that the former president had "a poor grasp of global affairs," including then-national security advisor John Bolton.

Bolton once said that Trump asked whether Finland was part of Russia.

Trump's former White House chief of staff Gen. John Kelly also recounted a similar event. Kelly said that the former president does not know any history at all, "even some of the basics on the U.S."

Hill openly wrote about Trump's lack of knowledge when it comes to international affairs and how it was a "major liability" for U.S. national security.

READ NEXT: U.S. State Secretary Antony Blinken, Defense Secretary Lloyd Austin Meet With Ukraine Pres. Volodymyr Zelenskyy in Kyiv    

Fiona Hill on Vladimir Putin

Hill also described her dinner encounter with Putin, saying that the Russian leader smelled "almost like he had stepped out of some special preparatory bath."

Hill noted in a New York Post report that it sounds bizarre, but she could smell that Putin was "freshly laundered."

The former Russian advisor added that Putin was not wearing cologne and was just all in command of himself.

She also noticed that the Russian president did not eat or drink anything, adding that Putin was "not much of a conversationalist" and barely even looked at her during the meal.

Hill said that the dinner happened while she was working as a national intelligence officer from 2006 to 2009 as an analyst of Russia and Eurasia.

Putin was reportedly visited by an oncologist on a regular basis and was speculated that he was suffering from thyroid cancer.

Russian Invasion of Ukraine

Russian officials have said that its forces are fighting for the "complete liberation" of Donbas, where Russian-backed separatists held significant territory before the invasion.

BBC News reported that Russian troops have been making slow progress in the east, with the capture of Rubizhne and Popasna.

However, their move forward around Izyum has been repelled and seemed to be focusing on trying to surround Severodonetsk.

Ukrainian forces' attack last week on Russian troops destroyed nearly all of a Russian battalion's armored vehicles.

Russia has now likely suffered losses of one-third of the ground forces it deployed in February.

READ MORE: Russia-Ukraine Crisis: Ukrainian Pres. Volodymyr Zelensky Says if Pres. Joe Biden Acted Sooner 'There Would Be No War'

This article is owned by Latin Post.

Written by: Mary Webber

WATCH: Trump Russia adviser Fiona Hill recalls dinner with ‘bizarre’-smelling Putin - from New York Post