Charts of 2007-2015 Q1: https://www.bea.gov/newsreleases/international/intinv/intinv...
More detailed data back to 1976: https://www.bea.gov/international/bp_web/tb_download_type_mo...
In short, the U.S. is now $7 trillion in the hole (39% of GDP), and most of that damage has been done in the past 5 years. In 2007 that hole was just $1.35 trillion. In 2014 alone the U.S. position worsened by $1.7 trillion.
-$1.2 trillion of this was due to exchange rates: other countries are running their printing presses faster than the U.S. is, so it is losing the competitive currency debasement race kicked off in 2008. This is not news, but it makes this number worse because it causes U.S. assets held by foreigners to appreciate faster relative to foreign assets held by U.S. citizens.
Price changes contributed another -$0.35 trillion. That is, even in local currencies, U.S. investments made by foreigners had a better return than foreign investments held by U.S. citizens.
Then all the way down at -$0.24 trillion was "net financial transactions", or the trade deficit, which is the thing Buffett's IC proposal would actually be able to control.
In other words, unless I have misunderstood something, balancing the trade deficit, or even running a substantial surplus is not going to solve these problems at the rate they are going. The question is how much of the current trends are sustainable.